Submission #766041

#	Time	Username	Problem	Language	Result	Execution time	Memory
766041		yusuf12360	Power Plant (JOI20_power)	C++14	0 / 100	1 ms	212 KiB

power

#include<bits/stdc++.h>
using namespace std;
int ans=1;
vector<int> res;
vector<vector<int>> adj;
string s;
void dfs1(int u=0, int p=-1) {
	res[u]=s[u]-'0';
	for(int pp : adj[u]) {
		if(pp==p) continue;
		dfs1(pp, u);
		if(s[pp]=='1') res[u]++;
		else res[u]+=res[pp];
	}
}
void dfs2(int u=0, int p=-1, int to_p=0) {
	int sz=adj[u].size();
	if(p!=-1 || s[u]=='0') ans=max(ans, res[u]+to_p-2*(s[u]=='1')*(sz>1));
	else {
		int cnt=0, mn=2;
		for(int pp : adj[0]) cnt+=(res[pp]>0), mn=min(mn, res[pp]);
		if(cnt==1) ans=max(ans, res[0]);
		else ans=max(ans, res[0]-mn);
	}
	for(int pp : adj[u]) {
		if(pp==p) continue;
		if(s[u]=='1') dfs2(pp, u, 1);
		else dfs2(pp, u, to_p+res[u]-(s[pp]=='1' ? 1 : res[pp]));
	}
}
int main() {
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int n; cin >> n;
	res.resize(n); adj.resize(n);
	while(--n) {
		int u, v; cin >> u >> v; --u; --v;
		adj[u].push_back(v);
		adj[v].push_back(u);}
	cin >> s;
	dfs1();
	dfs2();
	cout << ans << '\n';
	return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53